Caesarean birth greatly increases a baby's chances of developing
allergies, a study has found.
Infants delivered by C-section are five times more likely than
those born naturally to become allergic to common triggers such as
dust mites and pets, according to the research.
Scientists believe the babies are left vulnerable by avoiding the
journey through the birth canal, which would normally expose them to
their mother's bacteria.
Lead researcher Dr Christine Cole Johnson, from the Henry Ford
Hospital in Detroit, US, said: "This further advances the hygiene
hypothesis that early childhood exposure to micro-organisms affects
the immune system's development and onset of allergies. We believe a
baby's exposure to bacteria in the birth canal is a major influence
on their immune system."
Dr Johnson's team studied 1258 newborn babies and assessed them
when they were one month, six months, one year and two years old. By
two years of age, babies born by C-section were much more likely to
have developed allergies to triggers in the home such as the
droppings of dust mites and dead skin, shed by dogs and cats.
Umbilical cord and stool samples from each baby were analysed,
together with blood samples from both parents, breast milk and
household dust.
Maureen Jenkins, director of clinical services at Allergy UK,
said: "During a natural birth the baby travels slowly down the birth
canal where it ingests normal bacteria, which has been shown to aid
a healthy immune response and protect against allergy.
"In the case of a C-section, the baby has no contact with the
birth canal."